INVOLVEMENT OF WALL COMPONENTS IN ADSORPTION OF SILICONE ANTIFOAM TO SACCHAROMYCES CEREVISIAE

Abstract

The ability of Saccharomyces cerevisiae NCYC 366 to adsorb polydimethylsiloxane (PDS), dispersed in an aqueous emulsion containing stearate emulsifiers and cellulose‐based thickeners, is diminished after treatment with trypsin, KOH and HF; treatment with β‐glucanase initially caused an increase in binding which diminished on prolonged incubation. Trypsin and KOH removed most of the mannan, protein and phosphorus from isolated walls, while exposure to β‐glucanase removed about half of the glucan, protein and phosphorus. HF treatment removed most of the phosphorus but had little effect on the contents of other wall components. Cells treated with trypsin or β‐glucanase had pH‐mobility curves similar to those of untreated cells. Those treated with KOH or HF had lower mobilities at all pH values. Treatment of cells with each of the reagents except β‐glucanase lowered their capacity to bind fluorescein‐labelled antibody. The ability of cells to bind fluorescein‐labelled concanavalin A was decreased only after trypsin and KOH treatment. Treatment of PDS‐containing cells with trypsin, β‐glucanase or KOH caused release of bound silicone, the effect being smallest with β‐glucanase treatment. It is concluded that binding of PDS‐containing antifoam to yeast mainly involves ionogenic groups in the wall phosphomannan‐protein. 1977 The Institute of Brewing & Distilling